Grenade



Sept. 4, 1962 H. THWAITES ETAL 3,052,186

GRENADE Filed Dec. 22, 1944 Herman LT/iwarzhes George L. Maf/zeson 61 No x 1411 o United States Patent ()fifice 3 ,fi5Z,l8 5 Patented Sept. 4, 1962 3,052,186 GRENADE Herman L. Thwaites, Clark Township, Union County, and

George L. Matheson, Union, N..l., assignors to the United States of America as represented by the Secretary of Wai- Filed Dec. 22, 1944, Ser. No. 569,401 6 Claims. (Cl. 10265) This invention relates to a grenade, and more particularly to an incendiary grenade having a time delay fuze mechanism associated therewith.

One object of this invention is the provision of a grenade which is adapted to fire a predetermined time after it has been immersed in a liquid such as gasoline or water.

A further object of this invention is the provision of a grenade which when introduced into a receptacle containing gasoline or other inflammable liquid will burst the receptacle after a predetermined period of time and set fire to the inflammable liquid.

A still further object of this invention is the provision of a grenade which may be readily constructed, which has a positive time delay and firing characteristics, and which is safe to handle by the operator prior to and during placement.

A still further object of this invention is the provision of a grenade containing an explosive charge and an incendiary mixture positioned such that ignition of an inflammable fluid into which the grenade may be placed is insured after firing.

Other objects and advantages of the present invention will appear from the following description and the accompanying drawings in which:

FIG. 1 is a side view of an assembled grenade;

FIG. 2 is a top view of an assembled grenade;

FIG. 3 is a vertical section taken along the lines 3-3 of FIG. 2;

FIG. 4 is an exploded view showing component parts of the grenade prior to final assembly;

FIG. 5 illustrates a closure device for use with the grenade; and

FIG. 6 is a vertical section of a portion of a modified grenade.

In accordance with one embodiment of this invention the grenade comprises a body of an explosive, such as TNT, positioned adjacent a body of loose particulate magnesium. The explosive is set off by means of a time delay fuze. When the unit is placed in a tank or other receptacle containing a liquid hydrocarbon such as gasoline or the like or another liquid, the liquid causes an element in the unit to swell thereby releasing a cocked firing pin which causes the grenade to explode thus bursting the receptacle. The magnesium powder is ignited by the explosion and (in case of flammable liquid) the ignited magnesium particles set fire to the liquid escaping from the burst receptacle. In the specific embodiment described herein the release of the cocked firing pin contained in the fuze assembly is accomplished by the swelling action of a rubber washer or washers in gasoline, or other liquid hydrocarbon, whereby a retaining ring is withdrawn from around a split washer which holds the firing pin in its cocked position. When the retaining ring has been completely withdrawn from around the split washer, the split washer separates thus releasing the firing pin.

For a more complete understanding of this invention, reference is made to the attached drawing wherein it disclosed an incendiary grenade constructed in accordance with one embodiment of this invention. Referring now to the drawing, the grenade comprises a charge cup 14 threadably engaged with a fuze case 5 by means of a screw cap 13 and a primer holder 15. The charge cup 14 contains a plurality of TNT pellets 19 having a center hole through which extends a detonator 18. The TNT pellets 19 are spaced from the side walls and bottom of the cup 14 and this space is filled with magnesium powder 20. The magnesium powder preferably comprises a mixture of gradient size particles.

Within the fuze case 5 is contained a firing pin 1*1 threadably engaged with a firing pin nut 10 which is urged to the firing position toward a primer 16 by a spring 9. The end of the firing pin 11 opposite the primer [6 is provided with outwardly tapered shoulders abutting against corresponding inwardly tapered shoulders of a split washer 8. The split washer 8 is held in the position shown in the drawing by a retaining ring 6. It will be evident that when the retaining ring 6 is moved upwardly from around the split washer *8, the split washer is caused to separate because of the action of spring 9, and the firing pin 11 is driven against the primer 16.

The retaining ring 6 is secured to the shank of a perforated plunger 2 by means of a brass screw 7. Between the perforated under-shoulder of the plunger 2 and a shoulder of the fuze case 5 are positioned a Bakelite Washer 4 and two rubber discs 3. The rubber discs 3 are positioned between the Bakelite washer 4 and the perforated shoulder of the plunger 2 so that when the rubber discs swell on immersion in gasoline they will move the perforated plunger 2 upwardly thus withdrawing the retaining ring 6 from around the split washer 3.

Adjacent the upper portion of the fuze case 5 are provided two holes for receiving a cotter pin and pull ring assembly 1. When the cotter pin is in position, movement of the perforated plunger 2 in an upward direction is prevented. This pull ring and cotter pin assembly 1 therefore provides a safety feature to insure against pre mature firing of the device.

A secondary safety feature for the device is the provision of a rubber disc 17 compressed within the bore of the fuze case 5 at its open end directly above the perforated plunger 2. The rubber disc 17 is sprung into position and serves to hold the perforated plunger 2 firmly in position even after the pull ring and cotter pin 1 have been withdrawn. This supplemental safety feature is the subject of the copending application Ser. No. 569,400, filed December 22, 1944, of Herman L. Thwaites and Garland H. B. Davis and is described and claimed therein.

In operation of the above described device, the pull ring and cotter pin 1 is withdrawn by the operator and the device is ready for immediate placement. Accidental displacement of the perforated plunger 2 is presented by the rubber disc 17. The grenade is then introduced into a gasoline tank or other receptacle containing gasoline. The gasoline acts upon the rubber disc 17 causing it to swell and then to spring outwardly thus effectively removing itself from the end of the fuze case 5. At the same time the gasoline will enter through a central hole in the disc 17 and through the holes in the shoulder of the perforated plunger 2 and come into contact with the two rubber discs 3. The rubber discs 3 will then begin to swell by the action of the gasoline on the rubber. After a period of from four to eight hours the rubber discs 3 will usually have swollen sufliciently to push the plunger 2 upwardly the required distance to withdraw the retaining ring 6 from around the split washer 8. The force of the spring 9 urging the firing pin nut 10 and'the firing pin 11 in a downward direction causes the split washer 8 to be forced into the space left by the withdrawn retaining ring 6. When this happens, the firing pin is released and the spring 9 forces the firing pin 11 against the primer 16 which sets off the detonator 18 and the TNT charge 19. The resulting explosion bursts the gasoline container and the magnesium particles ignited by the explosion set the gasoline on fire.

In order to insure the ignition of the gasoline by the explosion, it is desirable that several things be borne in mind. For example, it has been found that best results are achieved when the charge cup 14 is constructed so as to permit a side burst. To .eifect this the end wall of the charge cup 14 is somewhat thicker than the side walls. Also a low density mixture of large and small particles of magnesium powder 20 are desirable in order to obtain the proper incendiary action. The mixture may range from 50-100 mesh particles to particles measuring x ,4 thick. The larger burning particles tend to be scattered into the area where ignitible proportions of air and gasoline vapors occur. Low density is obtained during assembly by refraining from excessive tamping or compressing the magnesium powder into the charge cup during loading. For use in ordinary automobile gasoline tanks it has been found that a unit containing about 9 grams of TNT and 8.5 grams of powdered magnesium will produce the desired effect.

The time delay of the device may be readily controlled by modifying the fuze assembly. For example, the time delay may be changed by varying the thickness of the split washer 8 and the retaining flange on the retaining ring 6. Also, if a shorter time delay is desired, a greater number of somewhat thinner rubber discs 3 may be employed so as to permit a more rapid penetration of the gasoline therebetween, thus increasing the rate of swelling. Also if desired, paper discs may be inserted between the successive rubber discs in order to cause the more rapid penetration of gasoline by the provision of capillary passages.

The time delay may be shortened by providing holes 211 in the fuze case 5 adjacent the rubber discs 3 as illustrated in FIG. 6, thereby permitting more rapid penetration of the gasoline to the discs 3. The holes 21 may be sealed with a cement that is not soluble in gasoline, but which can be removed by the user if the shorter time delay is desired.

It will be seen from the foregoing that the grenade of this invention may be readily manufactured. Many of the parts may be molded from synthetic resinous material such as Bakelite. Even the split washer 8 and the retaining ring 6 may be so made if desired. However, to insure proper firing and predetermined time delay it has been found desirable to form these parts of metal.

The unit may be transported in a disassembled condition if desired. Thus the unit may be separated between the screw cap 13 and the primer holder 15 and the d'etonator 18 may be removed so that the various parts may be carried separately. A closure for the charge cup 14 is provided in the form of a threaded plug 22 which may be inserted in the charge cup 14 when the fuze and detonator are removed. Prior to use, the detonator 18' is placed in position within the charge case and the fuze unit is, screwed into the screw cap on the charge cup.

While the above described device is particularly useful for destroying tanks containing gasoline or the like, it may be modified for use in receptacles containing other liquids. For example, spacing means such as felt washers may be employed to center the TNT pellets Within the charge cup 14 and a felt washer may be position be-; tween the pellets and screw cap 13. Also, the magnesium powder may be omitted from the charge cup 14 if desired and the cup may be entirely filled with TNT or other high explosive. Also discs of other material may be substituted for the rubber discs 3-. For example, discs could be used which are capable of swelling in water, such as gelatin or the like. The device then could be used for the destruction of Water tanks and boilers.

While a preferred embodiment of the invention is disclosed in the foregoing, it will be readily apparent to one skilled in the art that many modifications may be made t Without departing from the spirit and scope of the invention as defined by the appended claims.

We claim:

1. A grenade of the character described comprising a hollow, frangible, metallic external casing, a high explosive bursting charge for the casing enclosed in the casing, the said casing having an open end and an opposite end wall somewhat thicker than side walls of the casing for assuring lateral fragmentation of the casing, the explosive charge being apertured discoidal bodies having dimensions somewhat less than the inside dimensions of the casing, thereby defining a space between the said bodies and the said casing, the said bodies being disposed in direct contact with each other with the apertures thereof in registry, a detonator rod extending through the registering apertures of the said bodies, a particulate incendiary material enclosing the discoidal bodies of the explosive charge and filling the space intermediate the said bodies of the explosive charge and the casing and being in direct contact with the bodies of the explosive charge for ignition by flame therefrom incident to detonation of the explosive bodies, a closure plug for the open end of the casing, a detonator rod extending through the registering openings in the explosive charge, the said closure plug for the casing engaging the particulate incendiary material and the explosive charge and retaining the same against displacement, the said closure plug hav ing a centrally disposed opening therethrough, a primer holder mounted in the said opening and having an aperture therethrough registering with the detonator rod, a primer disposed in the said aperture adjacent to the detonator rod and actuatable upon impact for detonating the detonator and explosive charge, firing pin mechanism mounted on the primer holder in engagement the closure plug, and firing pin means in the said'mechanism disposed adjacent to the primer for imparting a detonating impact against the primer responsive to impact of the grenade against a target object, detonation of the primer in turn detonating the detonator rod and explosive charge, thereby fragmenting the grenade casing and igniting the particulate incendiary material.

2. A grenade of the character described, comprising a hollow frangible metallic cup having an open end and defining the external casing for the grenade, the said cup being interiorly peripherally threaded adjacent to its open end, a high explosive charge disposed in the casing and being of less diameter than the interior diameter of. the casing defining an enclosing space intermediate the said explosive charge and the casing, a particulate incendiary composition filling the said intermediate space, a detonator rod extending through the explosive charge by way of passage means provided therefor in the explosive charge, a closure plug threadedly mounted in the open end of the casing and having an internally threaded opening therethrough, a primer holder threadedly mounted in the said opening and having an opening therein in alignment with the detonator rod and communicating with an end recess in the primer holder, a'priming charge mounted in the end recess of the primer holder and extending into the said opening in the primer, holder closely adjacent to the detonator rod, the said priming charge being reactive under impact to detonate the detonator rod and thence the explosive charge for, igniting the incendiary material and fragmenting the external casing of the grenade, firing pin mechanism mounted on the primer holder, and a firing pin in the said mechanism for impacting against the priming charge for initiating the aforesaid detonation.

3. A grenade of the character described, comprising a hollow frangible metallic cup having an open end and defining the external casing for the grenade, ahigh explosive charge disposed in the cup and having a size and volume somewhat less than the interior-cf the cup for defining an intermediate :space between the explosive charge and inner walls of the cup, a particulate incendiary composition filling the said space and enclosing the explosive charge, detonator means for the explosive charge extending therethrough, and a closure assembly for the cup casing comprising a closure plug mounted on the open end of the cup in engagement with the explosive charge and incendiary composition for retaining the same against shitting in the cup, a primer disposed in the closure plug adjacent to the detonator means, and firing mechanism carried by the closure plug and including a firing pin adapted to impact against the primer for activating the primer for initiating detonation of the detonator means and the explosive charge, the said incendiary material being in contact with the explosive charge for ignition from the explosive charge responsively to detonation thereof, the external casing of the grenade also fragmenting responsively to detonation of the explosive charge for releasing both the ignited incendiary charge and explosion waves from the explosive charge.

4. A grenade of the character described, comprising a hollow frangible metallic cup-like casing having an open end and defining the external casing for the grenade, a high explosive charge disposed in the casing and having a size and volume somewhat less than the interior of the casing for defining an intermediate space between the explosive charge and the casing, which space completely surrounds the explosive charge, a particulate incendiary composition substantially completely filling the said space and completely enclosing the explosive charge in direct contact therewith, a detonator rod projecting through the explosive charge, and a closure assembly for the open end of the casing including a closure plug threadedly mounted in the open end of the casing in engagement with the explosive charge and incendiary material for preventing displacement thereof, the said closure plug having an internally threaded opening extending therethrough and communicating with the detonator rod, a holder for a primer charge threadedly mounted in the said opening and provided with a passage therethrough in axial alignment with the detonator rod, a primer charge mounted in the said passage adjacent to the detonator charge, and firing pin means mounted in the passage and defining a closure therefor, the firing pin means including a firing pin adjacent to the primer charge and adapted to impact against the primer charge to detonate the primer charge upon impact thereon for initiating detonation of the detonator rod and high explosive charge, thereby fragmenting the cup-like casing and firing the particulate incendiary material responsively to detonation of the high explosive charge.

5. A grenade as defined in claim 3 wherein the high explosive charge comprises molded pellets of trinitrotoluol (TNT).

6-. A grenade as defined in claim 3 wherein the high explosive charge is composed of superposed pellets of trinitrotoluol (TNT) having aligned openings therethrough defining a continuous passage extending through the pellets, and a detonator rod for the pellets mounted in the said passage and extending through the said pellets.

References Cited in the file of this patent UNITED STATES PATENTS 754,013 Reichenau Mar. 8, 1904 1,153,513 Nixon Sept. 14, 1915 1,316,005 Vautin Sept. 16, 1919 1,417,475 Weeke May 23, 1922 1,436,248 Hammond Nov. 21, 1922. 1,788,856 Bossono Jan. 13, 1931 1,898,073 Woodberry Feb. 21, 1933 2,314,614 Fisher Mar. 23, 1943 FOREIGN PATENTS 116,726 Germany Dec. 24, 1900 505,637 Great Britain May 15, 1939 853,365 France Dec. 7, 1939 

